This invention relates to a process for producing a hardened product of coal ash which has various uses (e.g. wallboard) as a fire-resistant civil engineering or construction material, especially a fire-resistant board.
In order to effectively utilize coal ash discharged from a thermoelectric power plant, there has been hitherto made an attempt of producing a hardened product of coal ash used as a civil engineering or construction material by mixing the coal ash with slaked lime or quickly lime. However the above-mentioned conventional method has not afforded a hardened product having practically sufficient strength.